Aug 13 (Reuters) - A U.S. jury on Friday awarded Optis Wireless Technology LLC and several related companies $300 million in damages after a second patent trial against iPhone maker Apple Inc (AAPL.O). A jury had previously found that Apple had infringed five Optis wireless standard essential patents and awarded $506 million in damages, but U.S. District Judge Rodney Gilstrap in Marshall, Texas, vacated that award in April and ordered a new trial to determine the amount of damages. In a statement, Apple said: "Optis makes no products and its sole business is to sue companies using patents they accumulate. We will continue to defend against their attempts to extract unreasonable payments for patents they acquire."